We've had no trouble with this fight since I split the orbs up.
One orb is for healer/tank/healer/tank (2 healer group).
The other orb is for all dps, starting with the highest and working down, unless we have melee which I send in first so they can stay on boss.
We can send 5 dps in to the orbs in the time it takes the 4 healer/tank group as the dps are in there for less time. We don't bother sending in the 6th dps and leave him on big add duty.
This also means you only deal with one set of adds at a time.
Range dps concentrate on the adds and interrupt them. Off-tank will nuke them too when no big add is up. We don't bother worrying about the Expel Corruption too much.
The one other thing we do is to stack so that the AoE healing is covering everyone. More important as the AoE damage ramps up.

I see a lot of good ideas here, so I'm just throwing our tactic in the mix. We let 2 dps, 1dps + 1 healer x3, then tanks if we are still above 50 %. Everyone soaks a black orb before getting cleansed in the other realm and after 50% and BL we let healers and tanks soak the black orbs. Our group is good with adds, so that has never been a problem.

Why would you ever send in a tank? Tank-trial is the hardest to survive..

We use following setup:
dps 1 & dps 2, both go in at pull
dps 3 & dps 4, soak one each and go in
dps 5 & healer 1, soak one each and go in
<tanks soak one each>
healer 2 soak to 100 and go in
healer 3 soak to 100 and go in

The tank trial is easy to survive and has less repercussions than sending a DPS in as far as releasing adds. As long as the tank moves out of Titanic Smash and interrupts Hurl Corruption there is essentially no reason that they should have any trouble surviving. (And it allows us to have our tanks soak all of the corruption)

The tank trial is easy to survive and has less repercussions than sending a DPS in as far as releasing adds. As long as the tank moves out of Titanic Smash and interrupts Hurl Corruption there is essentially no reason that they should have any trouble surviving. (And it allows us to have our tanks soak all of the corruption)

Exactly. Tank trial is not that hard once they get used to it.
Also means no-one except tanks (and maybe a melee) should be moving from AOE heals, making things so much easier.

But, it all comes down to what works for the group. As I already posted, we only send 1 dps in at a time which makes the adds much easier to control in the real room. Having 2 dps going in at a time was just causing us to have to handle double adds and giving us no benefit.